#include <sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<unistd.h>
#include<stdio.h>

int main(int argc,char **argv){
	int fd;
	int off_t1,off_t2;;
	fd=open("./test.txt",O_RDONLY);
	off_t1=lseek(fd,0,SEEK_SET);;
	off_t2=lseek(fd,0,SEEK_END);
	close(fd);
	printf("the size of the file:%d\n",off_t2-off_t1);


}
